Income Taxes - Earnings Before Income Taxes and Related Provision for Income Taxes (Detail) - USD ($) $ in Thousands	12 Months Ended
	Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2016
Income Tax Disclosure [Abstract]
Domestic	$ 27,787	$ 31,885	$ 44,795
Foreign	2,593	4,544	5,849
Earnings Before Income Taxes	30,380	36,429	50,644
Federal
Current	6,030	11,262	16,178
Income Tax Provision	6,531	14,872	18,415
Fixed asset basis differences and depreciation	410	(181)	(45)
Intangible asset basis differences and amortization	(4,052)	(1,158)	(744)
Currently non-deductible expenses and reserves	1,206	884	(694)
Stock-based compensation	1,379	(635)	129
Net operating loss carryforwards utilized	61	1,831
Tax credit carryforwards utilized	181	67	41
Other, net	(148)	99	181
Subtotal	5,067	12,169	15,046
State and local	1,066	1,900	2,421
Foreign	$ 398	$ 803	$ 948